Papers by Keyword: Concentration

Abstract: The paper presents the results of research on creating a high-strength cement composite using a complex additive. The optimal concentrations of additives of the Odolit-K hyper plasticizer in combination with bentonite have been determined. A significant decrease in the w / c ratio and an increase in the cement stone's strength was obtained. High-strength cement composites have been obtained with the optimal content of the complex additive. The volume-weighted average crystallite sizes were calculated using the Scherrer formula on the basis of X-ray studies. Deformation diagrams of statically loaded samples of prisms of the basic and control compositions of high-strength concrete were obtained. Deformation diagrams are investigated.

Abstract: Solutions with various concentrations of TiO₂ were obtained and studied. The morphology of the carbon fiber with TiO₂ coatings was investigated. The TiO₂ concentration significantly effects on viscosity and coatings formed on carbon fibers. The relationship between TiO₂ sol concentration and the mass oxide on the surface of carbon fibers was studied.

Abstract: The purpose of this work is to experimentally prove the possibility of modifying the surface of a material by exposure to a long-lived plasma formation (DPO). Under this action, the surface of the material experiences heat shock, since the contact time is about 100 ms. The paper deals with the usage of autonomous long-lasting plasm formations (DPO). The tasks of thermal processing, coating, thermal shock tests metallic and non-metallic materials are introduced in the given paper. Large stored energy (till 10 kJ) and high brightness temperature (4 500 K) at sufficient time of influence can determine the range of technological problems, where long-lasting plasma formations have advantages in comparison with plasmatrons. This paper presents the results of the tests of the thermal shock by the concentrated flow of electromagnetic energy, saved by long-lasting plasm formation.

Abstract: A steadily rising interest which specialists in various fields show towards the problem of hydrogen affecting metallic materials and causing their failure is connected to all-increasing requirements set on the durability of machines and equipment in operation. Metallic structures are most often surrounded by such environment which contains hydrogenous components or hydrogen itself (in chemical industry, power engineering, etc). And it leads to various types of degradation in metals (hydrogen embrittlement, hydrogen corrosion, and so on), which, in its turn, could cause catastrophic results. Ultimate strength is considered to be a representative parameter of the process of hydrogen degradation in steels. The authors cite the results of testing conducted on hydrogen-saturated specimens made of A516-55 steel which register a significant decrease in the ultimate strength. It is proposed to use a diagram which describes a fall in metal strength and transition of structural materials into their brittle states following an increase in hydrogen concentration. Discussion is made on criteria for hydrogen-saturated materials of metallic structures failing when a momentary overload occurs under default working conditions.

Abstract: References on microwave energy use were reviewed and it demonstrated wide use of this kind of energy in various sectors of national economy. However in ferrous metallurgy this type of energy practically is not used despite the fact that it holds much promise and offers a number of advantages over other kinds of energy. In this work an attempt was made to use microwave energy in ferrous metallurgy and it was implemented in terms of concentration process development for limonite ores of the Lisakskoye deposit with hydro-goethite being a base iron-bearing mineral. Qualitative and quantitative characteristics of the subsequent magnetic separation process were determined. The developed concentration process of the Lisakovskoye deposit ores with the microwave energy used for baking and magnetizing of intermediate concentration products was compared with the current deep concentration process of the Lisakovskiy Mining and Processing Works and its advantages were demonstrated. Technical and economic calculation showed that the concentration process with microwave energy used is more efficient than deep concentration process without the product baking; it allows a significant increase of iron recovery into the concentrate and provides additional profit to the Company.

Abstract: Due to the temperature and concentration determine the kinetic undercooling of interface growth and nucleation undercooling inside the melt, they play an important role in the solidification microstructure of the alloy. In this paper, the effect of temperature gradient and cooling rate on the dynamic undercooling was studied and the mechanism of the concentration at the solid-liquid interface on the kinetic undercooling during the continuous cooling process was analyzed. A calculation method for the coupling of temperature and concentration during Inconel 718 alloy solidification was developed, which can solve the problem that the concentration and temperature are difficult to be calculated at the same time in the numerical calculation.

Abstract: The detection of paraffin deposits in the systems of main oil pipelines today is a very important problem, since they lead to emergency oil spills, environmental disasters and economic losses both for the enterprise and for the country as a whole. This work is aimed at studying the physicochemical properties of asphaltic resin paraffins, as well as the mechanism of phase transition from liquid to crystalline. Such studies make it possible to estimate the absorption coefficient of the paraffin phase, which was previously not possible due to the complex nature of oil, consisting of hydrocarbons and many organic compounds of various molecular weights, and to provide high-precision non-contact measurements of the concentration of suspended asphalt-resin-paraffins in the oil flow in the pipeline. The analysis of the morphology and chemical composition of paraffins of various deposits is carried out, the dependence of the phase transition depending on the temperature gradient is determined.

Abstract: The elastic constants of tungsten-rhenium alloy single crystals were calculated by simulation atomic method using embedded method atom of interatomic potential. The found results show that elastic constants are proportional to the rhenium concentration up to 25 at% Re at room temperature. By following, we observed the elastic constant C₄₄ dependency of temperature and decreased of elastic constant C’=1/2(C₁₁-C₁₂) when the Re atom addition increases. We have found that a growing instability of the bcc crystal structure. Our parameter calculation model is in good agreement with experimental data.

Abstract: Electrospinning is a method for making nanofibers by utilizing an electric field produced by high voltage. Electrospinning process is influenced by several factors including the concentration of the solution, conductivity, viscosity, volatility, surface tension, electric field strength between the needle and the collector, feed / flow rate and environmental conditions which include temperature, humidity and air composition. Electrospinning parameters are used to optimize the size of the nanofiber, concentration of the solution and the distance of the nozzle to collector. In the process of electrospinning PVA solutions that are handled by high dc voltage gets an electrostatic force and electric field. The solution will elongate to form a Taylor cone, then a jet of polymer will undergo thinning and evaporation to form fibers in the collector. The results of morphological analysis using scanning electron microscopy (SEM) showed that the smallest nanofiber was obtained at a solution concentration of 5%, dc high voltage10 kV, and the distance of the nozzle to collector was 15 cms.

Abstract: Zinc is one of the important material in human blood because of its effect in defensive system work for properly and it plays an important role in growth, wound healing Medically zinc concentration effect directly in skin health so it's important to make a sensor for discover zinc and its concentration change in human blood for each of male and female. Optical fibers are used as a sensor for detecting zinc and its concentration by transmitted laser signal through the optical fiber by using different types (single mode fiber SMF, photonic crystal fiber PCF) by studying the results of output laser the detection can be seen for zinc concentration change, the design of small PCF which the same LMA_10 but smaller in its radius of core and cladding even the distance between cores. The smallest PCF size has the best detection for all zinc concentration change in blood all that was done by comsol Multiphysics 5.4 simulation program